Scientists have identified Earth's oldest-known impact crater, and in doing so may have solved a mystery about how our planet emerged from one of its most dire periods.
Researchers have determined that the 45-mile-wide (70-km) Yarrabubba crater in Australia formed when an asteroid struck Earth just over 2.2 billion years ago. The collision occurred at a time when the planet was believed to have been encased in ice and the impact may have driven climate warming that led to a global thaw.
"Looking at our planet from space, it would have looked very different," said isotope geology professor Chris Kirkland of Curtin University in Australia, one of the researchers in the study published in the journal Nature Communications. "You would see a white ball, not our familiar blue marble."